School-aged children with HIV infection remain a vastly understudied population. While sleep problems and fatigue have demonstrated negative effects on psychosocial, behavioral, and physical health status in medically healthy children and adults with HIV infection, no research to date has examined these effects on children with HIV infection. While recent research has revealed substantial evidence for bi-directional interactions between sleep and the immune system, particularly as pertaining to immune mediators (e.g., cytokines) and host defense, no studies to date have evaluated the relationship between sleep disturbances and the immune system in pediatric HIV infection. Therefore, a specific aim of this study is to test a potential pathophysiological mechanism regarding sleep problems, fatigue, sleep architecture, immune mediators (e.g., cytokines), HIV disease status, and psychosocial health in school-age children with HIV infection. This study will use a cross-sectional (correlational and within-subjects) design in which HIV+ children aged 7-12 will be asked to participate (N=90). This work involves recruitment of school-age children with HIV infection; caregiver informed consent and child assent; a preliminary screening for sleep problems; the completion of psychosocial measures by the caregiver and the child; a comprehensive diagnostic interview for the detection of sleep disturbances; an assessment of sleep architecture (with polysomnography) and fatigue (with multiple sleep latency test); and blood draw to assay plasma cytokine levels (with ELISA) and HIV disease markers (CD4+ count/percentage and viral load). The long-term aim of this project is to determine if sleep problems and fatigue may represent potential targets for interventions (e.g., pharmacological and/or behavioral) that would improve sleep, with associated improvements in psychosocial and physical health status (including immunity) in these medically vulnerable children.